The present invention relates to male terminal fittings and, more particularly, a male terminal fitting having a contact protrusion and a method of manufacturing the same.
Various attempts have heretofore been undertaken to develop a male terminal fitting of the type having a plate-shape contact protrusion as disclosed in FIGS. 1 and 2. In such a male terminal fitting, the plate shape contact segment 1 is fabricated first by stamping a conductive thin metal sheet in a developed stage and subsequently bending the thin sheet metal into a final product. In particular, the plate-shaped contact protrusion 1 is comprised of an elongated base plate component 2, and an overlapping fold plate component laterally extending from one end of the base plate component and folded to lie over the base plate component 2. a distal end 3a of the overlapping fold plate component 3 is further folded toward the base plate component 2 such that a tabular portion 4 is formed. The presence of the hollow portion 4 enables the plate-shape contact protrusion 1 to have a desired thickness L1 even when using the thin sheet material.
However, since the tabular portion 4 is internally formed when forming the overlapping fold plate component 3 toward the base plate component 2, central portions of the base plate component 2 and the overlapping fold plate component 3 are caused to be collapsed in depths L2, L3, respectively, due to external press forces exerted thereto during the forming operation as shown in FIG. 2.
With such deformations, the base plate component 2 and the overlapping fold plate component 3 do not have desired flatness, resulting in a decrease in contact surface areas against mating walls of an associated female terminal fitting with a degraded reliability in electrical contact.
To address such an issue, another attempt has been proposed to develop a male terminal fitting whose plate-shaped contact protrusion is shown in FIGS. 3 and 4, wherein a base plate component has a longitudinal extension 7 which is folded back to form an overlapped structure on which overlapping plate components 6, 6 are folded inward to lie on the overlapped structure as disclosed in Japanese Patent Provisional Publication No. 10-3956. With such a structure, even when the plate-shape contact protrusion is exerted with the external press forces, the presence of the overlapped structure 7, which is laminated with the overlapping plate components 6, 6, avoids the central portions of the base plate component 2 and the overlapping plate components 6, 6 from being collapsed.
However, with a particular structure proposed in such a Japanese Provisional Publication, the presence of the longitudinal extension 7, which longitudinally extends from the distal end of the base plate component, needs an elongated sheet material with a remarkably increased width, causing an increase in a material cost and an increase in waste material.
Further, the presence of a bending step for bending the longitudinal extension 7 such that it is folded back to the base plate component 5 is reflected in an increase in the number of bending formation steps, thereby increasing the manufacturing cost of the male terminal fitting.